TABLE 2.

Microglia phenotypes in patients with Alzheimer’s disease revealed by single-cell technologies.

References	Patients	Method	Brain region	Microglia state/cluster (gene signature)
Del-Aguila et al., 2019	3 patients with Mendelian or sporadic AD	snRNA-seq	parietal lobes
Mathys et al., 2019	48 AD patients	sRNA-seq	Prefrontal cortex
Grubman et al., 2019	6 AD patients	sRNA-seq	Entorhinal cortex
Zhou et al., 2020	11 AD patients with TREM2-CV and 10 bearing TREM2-R62H	snRNA-seq	Dorsolateral prefrontal cortex
Lau et al., 2020	12 AD patients	snRNA-seq	Prefrontal cortex	Reduced microglia subpopulation that expresses genes which participate in synaptic pruning (C1QA, C1QB and C1QC, encoding complement component 1q) or encode cytokine receptors (IL4R and IL1RAP)
Nguyen et al., 2020	15 AD patients	snRNA-seq	Dorsolateral prefrontal cortex	4 microglia subpopulations: homeostatic, motile, amyloid responsive, and dystrophic microglia
Gerrits et al., 2021	10 AD donors with only Aβ pathology or both Aβ and tau pathology	snRNA-seq	Occipital or occipitotemporal cortex	AD1 microglia population express DAM genes, and are enriched with AD risk genes and correlated with tissue Aβ load; AD2 microglia express glutamate receptor GRID2 and are correlated with tau pathology

Blue, downregulated signature genes; red, upregulated signature genes. AD, Alzheimer’s disease; DAM, disease-associated microglia; Aβ, β-amyloid.